The present invention relates to transducers in general, and more particularly to transducers which are especially suited for use in power tools, particularly in power screwdrivers, for measuring torque transmitted, or relative angular displacement occurring, between a driving and a driven member.
There are already known various constructions of transducers of the above type. In one conventional construction of the transducer, which is known, for instance, from the published German patent application DE-OS No. 29 51 148 and the corresponding U.S. Pat. No. 4,356,732, a torsionally deformable member is interposed in the chain of transmission between the motor and the driven screwdriving member. Two slotted sleeve-shaped members are connected to the end portions of this deformable member for joint angular displacement therewith about the axis of the deformable member when torsion is applied to the latter and deforms the same. As the two sleeve-shaped members are angularly displaced relative to one another, they influence the magnetic field existing at the vicinity of the deformable member so that the changes can be and are detected by appropriate equipment to obtain the extent of such angular displacement and from the same the magnitude of the torque.
As advantageous as this construction may be in some respects, it is considered in the above application by itself, and the question of its mounting on or incorporation in the housing of a power tool or the transmission train thereof is not addressed at all in this application. Experience has shown that, especially when the arrangement of this type is to be used in power screwdrivers, there are encountered various problems, especially when it is desired to obtain a construction which is advantageous from the manufacturing, and thus from the economic, point of view. In addition thereto, the problems existing in transducers proposed prior to the aforementioned German application and relating to the way in which the electric signals derived from the transducer or the detecting arrangement thereof are transmitted to suitable indicating or evaluating equipment are present in the arrangement according to this prior German application as well.